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Tesla Coils : How music can be generated by electricity

Did you know that you could make a whole song by just letting electrical current flow trough a Tesla coil? Maybe the whole Super Mario – theme?

How is this possible?

Introduction

To answer that question we first have to know what a tesla coil exactly is. The first Tesla coil was invented bij Nikola Tesla, in 1891. A Tesla coil consists of different LC-circuits (inductance-capicitance) that generate a high voltage alternating current, also known as AC-current. Further it consists of 2 big coils that are magnetically coupled. In order for the Tesla coil to work the 2 coils have to be on the same resonance frequency. This resonance frequency is a frequency where a system can store a lot of vibrational energy with just small forces that transmit this energy. When this is done, the coils are tuned and ready to produce ‘music’.

Why do we hear the electricity ?

The LC-circuits pump a high energy current true the coils , and the frequency output of the coil is generally around 100-1000 kHz. So, the frequency of the sparks you see coming out of the coils is around these values, but how is it possible humans can hear this ? Our hearing range is about 20 Hz till 20 kHz, right? And we al know it decreases while you get older. But how is it possible we can hear these 100-1000 kHz frequency’s ? Well, the truth is, we don’t ‘hear’ the 100-1000 kHz frequency’s.

When these sparks shoot out from the coil a capacitor ,which is charged at his full capacity, wil discharge into the primary coil. This coil will begin to oscillate and it will create a magnetic field, that will couple to the secondary coil. The greater the magnetic coupling between these coils , the shorter the time is required to complete the energy transfer. This will go on for a couple of cycles and the voltage in the coils will rapidly increase till the air surrounding these coils will undergo what we call ‘dielectric breakdown’. This means the energy is so high the gas molecules will become ionized, forming the purple discharge shown on the video above. The air will begin to vibrate on a frequency of 100-1000 kHz. We only hear the sound of air becoming ionized. So the trick in making music is ionizing the air at a certain amount of times in a second. Imagine you want to produce a ‘la’ , you have to switch the Tesla coil on and off about 400 times per second. Because a ‘A’ has a frequency of 400 Hz.

If you want to play a song on a Tesla coil, you have to write a program on a computer that communicates with a micro-controller that is connected to the LC-circuits. This program has to be able to transform all the notes of a song into 1’s or 0’s. The 1’s will tell the micro-controller to put the circuit on, and the 0’s will tell to put it off. What will you hear if you just give continously a 1 to the system? You will just hear one loud pop. You can see the Tesla coil acting as one big speaker, making the air vibrate by ionizing it.